Based On Deepwater Riser Vortex-induced Test Device Vibration Monitoring Systems

In Marine environment, the fluid through the riser which produces alternatingdiarrhea vortex on the back flow surface caused the vortex-induced vibration.Vortex-induced vibration is not only the result of a fluid solid coupling, but also afusion of fluid mechanics and structural mechanics; But the coupling reaction candramatically reduce the useful service life of the riser, once the riser fatigue damageoccurs, the oil spill will make the project suffer losses, even lead to seriousenvironmental pollution and secondary disasters, so the vortex-induced vibration ofdeep-sea riser is an important factor to riser design.This paper analyzes the physical model of vortex-induced vibration in deep-seariser, through the design of the experimental platform and the analysis of testingsystem software the riser to know the vortex-induced vibration responsecharacteristics and the influence of other factors under different external flow velocity,and analyze its modal parameters. By compared the experimental data ofvortex-induced vibration from different universities to strengthen the effectiveness ofthe experiment, and completed the vortex-induced vibration experimental study ofMarine riser gradually.Firstly, the vortex-induced vibration theory of riser are analyzed in detail, bycombining the influence of the parameters related the outside world in thevortex-induced vibration experiment, especially the correlation of the velocity, the toptension and vibration. Subsequently, the vortex-induced vibration experiment schemeis determined by referring to the research schools and scientific research institutionsrelated to the vortex-induced vibration, and comparing the advantages anddisadvantages of the experimental equipment.Then finished the hardware platform of vortex-induced vibration in lab and thedesign of data acquisition system. Through the regulation of top tension and speed ofriser bracket, to realize the simulation of vortex-induced vibration under oceanconditions; The vortex-induced vibration of acquisition system is designed to obtainthe real-time, synchronous data, and laid a foundation for the vortex-induced vibrationtheory research and explore the suppression method.Finally carried out the experiment of the model of the riser vortex-inducedvibration, designed the experimental scheme of different factors, this paper expoundsthe experimental data analysis method. Acquire fairly reliable experimental data by decorate a small amount of sensor, analyzes the dynamic characteristic of thevortex-induced vibration of Marine riser, including natural frequencies, vibrationfrequency and displacement transformation and modal, preliminary discussed thegeneral rule of vortex-induced vibration.This paper draw the hardware structure of the Marine riser vortex-inducedvibration from the Universities and research institutions at home and abroad,establishing the corresponding riser model and acquisition system, through a largenumber of experimental data analysis and comparison demonstrate the validity of thetest apparatus and collection system design. According to the result of the experimentand design results preliminarily explores the Marine riser vortex-induced vibration ofdynamic characteristics, laid a foundation for subsequent vibration suppressionexperiment and fatigue analysis.